Too low for that amount of work.
An artist would have to go through your story and convert it into a comic script.
Then, thumbnail the comic pages while considering panel and page flow, and word balloon placement.
Design characters and make a character sheet to make sure their design stays consistent.
Then, they must pencil and ink the pages, which could take 16 hours of work per page. This depends on the complexity and detail.
Then, spend time coloring it if you want it in color.
Also, they would have to letter it.
$20 per page if it is a 50-page oneshot is really low.
This is a list of indie comic page rates.
Work for Hire/Page Rate MAINSTREAM INDIE Script $80-100 $25-50 Covers $600-700 $200-500 Line art $200-300 $100-250 Colour art $80-135 $20-80 Letters $20-25 $10-20 Whether you're being offered lower than standard page rates or not from a publisher, it is important that there remains an ongoing...
fairpagerates.com